In general, a silver halide color photographic material comprises silver halide emulsion layers which are sensitive to three primary colors, i.e., red, green and blue. The material is adapted to be subjected to a so-called substractive color process by which three couplers in the respective emulsion layers are developed to colors complementary to that to which the respective layers are sensitive, to reproduce a color image. The color image obtained by photographic processing of such a silver halide color photographic material normally comprises azomethine dyes or indoaniline dyes produced by the reaction of an oxidation product of an aromatic primary amine color developing agent with a coupler. The color photographic image thus obtained is not necessarily fast to light, moisture and heat, and thus is susceptible to discoloration of dye image and hence deterioration of image quality when exposed to light or stored under the conditions of high humidity and temperature for a prolonged period of time.
Image discoloration is a fatal disadvantage to recording materials. In order to eliminate this disadvantage, various approaches have been proposed. For example, a new coupler which provides a dye having a high fastness has been developed. Further, the use of a discoloration inhibitor has been proposed. Moreover, the use of an ultraviolet absorbent has been proposed to inhibit the deterioration of an image by ultraviolet rays.
Among these approaches, the use of a discoloration inhibitor exerts a great effect of inhibiting the deterioration of an image. For example, the addition of hydroquinones, hindered phenols, catechols, gallic esters, aminophenols, hindered amines, chromanols, indanes, ethers or esters obtained by silylating, acylating or alkylating the phenolic hydroxyl group in these compounds, and metal complexes has been known.
These compounds are considered to serve as dye image discoloration inhibitors. However, they cannot fully meet the customers' growing demand for high image quality. Further, the compounds cause hue change, fog, maldispersion, or microcrystallization after coating of the emulsion. Therefore, the compounds do not go so far as to provide overall excellent effects for color photography.
More particularly, the use of a compound obtained by substituting a phenolic hydroxyl group with an alkyl, as a discoloration inhibitor is proposed in JP-B-56-24257, JB-B-61-46819 (The term "JP-B" as used herein means an "examined Japanese patent publication"), JP-A-56-52747, and JP-A-60-262159 (The term "JP-A" as used herein means an "unexamined published Japanese patent application"). Although all the disclosed compounds exert a discoloration inhibiting effect, they cannot fully meet the strong demand for enhanced image fastness.